Hey Ray et al.... I purchased this saw a while ago on our favourite on line auction but you will see why I couldn't resist. This 8" brass back has a nice open beech handle held in place by two split nut screws. The unusual solid brass back is shaped with a round tube over a flat that holds the blade in place. The flat has the SLACK SELLARS & GRAYSON stamp, flanked by IMPROVED CAST STEEL and SHEFFIELD and again flanked by a stylized "SWIFT" and the word SPEED (Corporate logo) and on the far right NO 2226. HSMB suggests they were around from 1833 -1856 but Ray has Slack alone in Whites in 1833 and Slack, Selllars and Grayson in Whites 1849 and 1852. I tried to search the British patent records for the NO2226 but that seemed to require payment which I at this point wasn't ready to invest in. I am wondering if someone has free access in order to look up the patent to see how it might have been an improvement on the traditional brass back or was it a gimmic. I have not seen any in my travels so I don't know if it really took off. enjoy. Joe S.